“The polls got it wrong.” We hear this a lot when election outcomes don’t match pre-vote predictions. But what about the exit polls – the Election Day surveys that pollsters and pundits use to tell us what really happened? Turns out, there is a lot those tallies miss – particularly when it comes to older voters.

AARP commissioned an analysis by Echelon Insights of how many people in different age groups actually voted last November using what campaign pros call the ‘voter file’ – state by state data on registered voters and their voting activity. This research revealed some really interesting things.

First, the 2016 exits polls significantly underestimated turnout of older voters. Looking at counts of actual voters in 42 states (the remaining 8 and the District of Columbia do not keep track of voters’ ages), more than half of the 2016 electorate – 55% — was age 50 and up. This is a full nine percentage points higher than the 46% shown in the national exit polls. In fact, 50+ voters topped 50% in every one of the states where voter file data is available.

Second, voters age 65 and older are the most consistently undercounted. According to national exit polls, this segment of the older voter population was 16% of the 2016 electorate, when the true share is closer to 25%. And, all of the 25 statewide exit polls conducted in 2016, underreported voters age 65 and older, some by more than 10 percentage points.

Why is this important? The role of older Americans in deciding elections should not be understated. Americans age 50 and up were not only the largest single voting bloc by age in the last election – they were the majority of voters. This is a trend that we’ve seen over the last few election cycles and one that will continue in 2018.

In fact, older voters will be even more important in 2018 than they were in 2016. Historically, older voters make up an even higher share of the electorate in midterm elections, when participation of younger voters – who are more likely to vote in Presidential years — drops. In 2014, almost 60% of the 65+ and close to half of 45-64 year olds reported voting – compared to a little over a third of 35-44 year olds and less than one-quarter of 18-34 year olds.

This statistical reality means that in most races, across both red and blue states, older voters pick the winner. They are perhaps the most important swing voters in the country. In 2016, the 50+ voted for the winning candidate in 17 out of 19 Senate races where we have exit poll data by age. (In Nevada and New Hampshire, the 65+ voted for the winner, while the 50-64 voted for the other candidate.) There was a similar story in 2014. Looking at 23 Senate races, all but one of the winning candidates carried 50+ voters.

With 2018 on the horizon, candidates of both parties need to think about – and talk to – older voters in their states and districts. They are the nation’s most reliable voters. They are informed and engaged . . . and they make up their minds early. So, word to the wise . . . there’s no time to waste.